Wire coating die



- vHi5 Attorn y- Inventor: Robert W. M

Feb. 3, 1942- R. w. MuN

WIRE COATING DIE Filed July 17,

To TA KE'UP REEL Patented Feb. 3, 1942 UNITED, STATE s PATENT OFFICE I wmr: cparnve pm Robert W. Schenectady, N. Y ascignor to General Electric Company, a corporation of New York Application my 11, 1940, Serial No. 345,991

9 Claims.

This invention relates to apparatus for coating elongated articles, such as wire and the like, of'rectangular cross-section with liquid coating compositions, for example, enamels, varnishes,-

The invention'is especially conlacquers, etc.

cemed with the novel applicator or die assembly hereinafter, for brevity, referred to as a die, by the use of. which wires or other elongated articles of substantially rectangular orsquare cross-section, hereinafter referred to as wires of rectangular cross-section, may be effectively and economically coated with-liquid coating compositions including a viscous solution of a resinous sembly and suitable supporting means therefor;

Fig. 3 is a side view of the die assembly shown in Fig. 2; Fig. 4 is a top view thereof; Fig. 5 is a view of some of the elements of the die prior to assembly and Fig. 6 is a cross-sectional view of the die member and wire taken along lines 6-6 of Fig. 4.

The demand for rectangular wire provided with thin insulating films of organic enamel or var nish is rapidly increasing. However, as rectangular or substantially rectangular wire is ordinarily prepared by passing a wire of circular cross-section through an ordinary pair of rolls or through turks-head rolls, the resultant product is not always of uniform or constant crosssection. Thus, the insulation of such wire by means of ordinary rigid dies is usually impractical as any die large enough to pass the larger or thicker portions of the wire will apply too heavy a layer of enamel or varnish to those portions of the wire of smaller or thinner cross-section. Furthermore, even in the insulation of rectangular wires of substantially uniformcrosssection, it is necessary to have a die with an opening closely corresponding to the cross-section of the wire being run, the clearance between the die and the wire being of the order of a few thousandths of an inch, in order that a film of enamel of proper thickness may be applied to the wire. As a number of layers or films of insulating varnish are ordinarily applied to each wire, it is usually necessary to use a series of dies, each die having an opening correspondingly larger than that of the previous die by the thickness of the baked coating applied to the wire by the previous die.

. In accordance with this invention, I have provided a simple and inexpensive die adapted for usewith rectangular wires of various and irregular cross-sectional sizes which die is so constructed and arranged as to follow closely any irregularities in the wire and to maintain a con-.

stant clearance between the die and the wire sur-- faceso that the same die may be employed in coating a plurality ofv wires of different sizes as well as the same wire having different thicknesses of baked enamel thereon. .The die .is easily assembled about the wire and removed therefrom and, in addition to being self-conforming, that is, being adapted to follow variations in the cross-sectional size or shape of the rectangular wire, the die also is self-centering on the wire thus permitting the application of a layer of coating material of equal and uniform thickness on all four sides of the rectangular or square wire. I

The manner in which my invention may be applied to conventional wire coating apparatus is schematically illustrated in Fig. 1. As shown in this figure a wire I is drawn from a payofl reel 2 and under a guide sheave 3 immersed in liquid coating material 4 contained in a container or trough 5.

During its passage through the liquid coating material 4 the wire I is provided with a quantity of coating material, the excess of which is removed from the wire by die 5 forming the subject matter of myinvention. From the die 6 the wire now provided with a thin, uniform film or layer of coating material passes through an oven 1 containing suitable heating means such as electric heating elements 8 and then over a driving sheave 9. From the driving sheave 9 the wire is either recirculated through the coating material 4, die 6 and oven 1 to receive additional layers of baked coating material or is passed over pulley ID to a suitable take-up reel (not shown). The die 6 of my invention-"is supported above the'ccating bath 4 by suitable supporting means I such as that'shown in Fig. 2 as comprising an anchor plate ll adapted to be fixedly mounted at the base of the oven 1; U-shaped member l2 swivelly mounted at the base of the U on the anchor plate I I by means of screw l3; and a pair I of arms I4 and li-pivotally mounted at the ends of the U-shaped member l2 and resiliently biased toward one another by an arc-shaped spring member l6. Pivotal mounting of arms I4 and I! may be accomplished, for instance, by means of screws l1 and I8 passing through eyelets, such as indicated by numeral |4a, provided at the lower ends of the respective arms. The upper ends of each of the arms l4 and I 5 are bent inwardly to form prongs adapted to engage and hold the die 8 as will be more.-fully described hereinafter. mounted on the upper ends of arms l4 and |5 is capable of limited movement in any horizontal direction. 1

The die assembly proper adapted to remove excess coating material and to provide the wire passing therethrough with a thin uniform layer of enamel comprises a plurality of die members By this arrangement, the die 3v 2|, 22, 23 and '24 slidably interlocking to form a rectangular die opening or passage. Alternate die. members, specifically members 2| and 23, of

substantially identical design" and whose faces form opposite sides of the die opening, are ordina'rily somewhat wider than the remaining members 22 and 24 and are each provided with rather deep recesses 25 and 26 extending transversely across their faces. These recesses are adapted to receivetongues 21, 28, 29 and 30 provided on the sides of die members 22 and 24. These die the minimum width of the rectangular wire to be'coated by means of'the die assembly.

By this arrangement in which the tongues pro-.

lecting from die members 22 and 24 are capable of sliding in and out of or along the grooves provided in die members 2| and 23, it is possible to vary the relative positions of the various die members and thus to vary the size and dimensions of the die opening defined by these members.

The die opening proper, serving to control the thickness of the layer of enamel applied to the wire, is actually defined by the portions 3| and 32 of die members 2| and 23 above recesses 25 and 26 in cooperation with the upper portion of the faces of die members 22 and 24 including the T projecting tongues thereon. The size of the die opening with respect to any particular wire,

that is, the clearance between the face of the die and the wire, is determined by the height. of a plurality of parallel ridges 33 provided on the lower portions of the respective die members and shown in the drawings as running vertically along the die face up to the recesses 25 and 26 of die members 2| and 23 and a corresponding distance up the face of die members 22 and 24,

These ridges contact the surface of the wire" moving vertically through the die assembly and thus serve to space the upper portions of the die members defining the die opening proper from the wire.

The grooves 34 between ridges 33 permit a supply of enamel to be carried up through the die assembly to the die openingproper and also permit drainage of the excess enamel from the upper portions of the die back to enamel bath 4. This arrangement in effect results in a slight ofiset of the tops of each of the die members with respect to the plane surface defined by the tops of the-parallel ridges so that a constant clearance between. the upper portions of each of the die members and the wires is maintained irrespective of the varying sizes of the'wires.

U-shaped springs 33 and 33 the ends of which fit respectively into holes 31 and 33 provided in die members 2| and 23 and hole'33 in member 24 and a similar hole provided, but not shown, in die members22 serve. as means for holding the assembled die members in operative relationship about the wire and thus in conjunction with the ridges 33 serve to maintain a constant clearance between the wire and the die opening proper irrespective of any variations in the size of the wire passing'through the die assembly. Holes 40 and 4| centered in the lower portions ofdie members 2| and 23 having a diameter somewhat larger than the diameter of the ends of arms l4 and li'receive the prongs at the ends of these arms and thus prevent the die from travelling with the wire in its upward movement through the coating apparatus. Due to the fact that the arms I4 and I5 are pivotally mounted on the U-shaped member H which in turn is swivelly mounted on the anchor plate II, a free, although limited, movement of the die assembly is possible to permit the exact centering of the wire within the die even though the die assembly may be mounted somewhat out of line of travel of the wire between guide sheave 3 and driving sheave 3. The limited displacement permitted by this supporting means is also suflicient to compensate for any whip in the continuously moving wire.

It is to be understood that means other than example, one may use a. die stop comprising a pair of spaced parallel fingers integrally attached -to the oven walls in such a. manner that the pro- '40.

jecting end portions thereof'extending on each side of the wire contact the top of the die assemblyto prevent the die from traveling upwardly with the wire.

The operation of the die assembly is best understood by reference to Fig. 6, representing an enlarged cross-sectional view along the line 8-6 of Fig. 4. As shown in this figure, some of the enamel carried up through grooves 34 by the moving wire collects in the open portion of recess 25 of die member 2| and is either returned to the coating bath through the same grooves or is applied to the wire as a thin uniform layer 42 by the upper portion 3| of die member 2|.

By this arrangement it will be seen that I have provided a self-centering die capable of being used with rectangular wires of various sizes and cross-sectional shapes, the upper limit in the size of wire being that at which projections 21, 23, 23 and 30 of die members 22 and 24 can no longer be introduced into recesses 25 and 26 of die members 2| and 23 when the die members are assembled about the wire.

bers having transversely extending recesses in each of said members, the other of said pairs of die members having tongues projecting therefrom adapted to slide in said recesses, and means for holding said die members in operating relationship about said wire.

2. A'self-centering expansible rectangular wire terlocking die members, portions of the surfaces of each of said die members cooperating to form a rectangular die opening for a wire to be coated, the remaining portions of said die members being provided with means comprising, a plurality of parallel ridges adapted to center said wire in said die opening and to maintain a constant clearance between the surfaces of the wire and the surfaces of said die members forming said rectangular die opening, and means for maintaining. said die members in slidable interlocking engagement about said wire.

3. An expansible rectangular wire coating die coating die comprising a plurality of slidably inhaving, in combination,a plurality of slidably interlocking die members cooperating to form a.

rectangular die opening adapted to receive the wire to be coated, each of said die members having a plurality of parallel ridges extending vertically along the face thereofyaltemate die members having horizontally extending recesses therein adapted to receive in slidable engagement tongues projecting from the remaining die mem-v bers, and spring, means for maintaining said die members in slidable interlocking relationship about said wire.

4. An expansible die assembly for use in coating rectangular wires comprising a plurality of interlocking plates defining a die opening through which wire to be coated isadapted to pass, certain of said plates having recesses there-' in extending transversely to the direction ,of travel of the wire, the remainder of said plates having laterally extending tongues adapted to" slide in said recessesso that the dimensions of 'the opening defined by said plates may be varied to accommodate unlike dimensioned wires.

5. An expansible die assembly for use in coat-- ing rectangular wires comprising two pairs of plates defining a die opening through which wire to be coated is adapted to pass, opposite plates of one pair having recesses therein, opposite plates of the other pair having tongues adapted to slide in said recesses so that the dimensions of the opening defined by said plates may be varied to accommodate wires of different size.

6. Aself-centering expansible coating applicator for wire comprising a plurality of relatively movable die members, portions of the surface of each of said die members cooperating to form a die opening for a wire to be coated, other portions of said die members being provided with means engaging the wire to center the wire in said die opening, and to maintain a constant clearance between the surface of the wire and the surfaces of the members forming said die opening, and means for biasing said die members into operative position about the wire.

-7. A self -centering expansible coating applicator for wire comprising a plurality of relativelymovable members, portions of the surface of each of said die members cooperating to form a die opening for a wire to becoated, other portions of said die members being provided with a plurality of parallel ridges engaging the wire to center the wire in said die opening and to maintain a constant clearance between the surface of the wire and the surfaces of the members forming said die opening.

8. A device for applying a coating of substantially uniform thickness to wire or the like, comprising, in combination, movable means provided with a surface spaced a predetermineddistance from the surface of the wire to apply a predetermined thickness of coating to the wire and means in contact with the wire and. movable in response to variations in the surface of the wire to maintain saidapplying surface at said predetermined distance from the wire in accordance with variations in the surface ofthe article.

9. In a device for use in coating wire by a continuous process, a movable member having a surface spaced a predetermined distance from 7 the member in response to variations in'the size of the wire to maintain said surface at the said predetermined distance from the surface of the wire. I

ROBERT W. MUNGALL. 

